The invention relates to electrically rotating machines.
Electric motors or generators for producing electrical power have windings through which current passes. These run in a rotor and/or a stator. The rotor and/or the stator consists, if windings run herein, substantially of a laminated core. Laminated cores are composed of sheets stacked one on top of the other and produced in most instances by means of a stamping process. The sheets are firmly held together using a fastening mechanism, for instance a screwed connection. The windings through which current passes heat up during operation of the electrically rotating machine and emit a large part of their heat onto the laminated core. There is therefore the need to cool these laminated cores. In order to cool the laminated core, air can flow through cooling paths in the laminated core in order to absorb the excess heat. The air flow often passes through cooling paths in the rotor, which open out into cooling paths in the stator. After passing through the cooling paths of the stator, the air flow is in most cases emitted into the environment. These cooling paths begin in the rotor and conduct the air flow outwards through an air gap between the outer side of the rotor and the inner side of the stator into the adjoining cooling paths. If the gap on the end faces of the rotor and/or of the stator is not constricted, a significant part of the air flow escapes through this air gap between the rotor and the stator before it reaches the cooling paths of the stator.
The Swiss Patent application No. 461617 discloses that the gap between a rotor and a stator of an electrically rotating machine can be constricted by means of rings, in order to prevent the lateral escape of a cooling gas through the axially running air gap.